Name:______Per:______

Biology Unit 4: Metabolism

Essential Skills

4-1. Be able to name the reactants and products of Aerobic Respiration.

4-2. Be able to name the reactants and products of Photosynthesis.

4-3. Explain how the reactants and products of photosynthesis and respiration relate to each other.

Study Guide

Cellular Respiration

  1. Write the overall equation for Cellular Respiration (label the reactants and the products).

C6H12O6 + O2 à CO2 + H2O + ATP

Glucose + oxygen à carbon dioxide + water + energy

(Reactants) (Products)

  1. What is the purpose for cellular respiration in cells? What types of organism perform cellular respiration?

Cellular Respiration produces energy (ATP) for the cell. All organisms perform some type of cellular respiration. Prokaryotes mostly perform anaerobic respiration. Eukaryotes perform aerobic respiration.

  1. What is ATP? Why is it so important for all living things?

ATP is chemical energy for the cell. Organisms use this energy to maintain homeostasis, reproduce, grow, carry out chemical reactions and perform active transport.

  1. Explain the differences between aerobic and anaerobic respiration by filling out the chart below:

Location of Process in Cell / Is Oxygen Used? / Amount of ATP produced? / Organisms that do this process
Anaerobic Respiration / Cytosol / No / 2 ATP / Prokaryotes & animal muscle cells
Aerobic Respiration / Mitochondria / Yes / 38 ATP / Eukaryotes
  1. What happens after Glycolysis if oxygen is not present? How does this help make more ATP?

The pyruvic acid produced during glycolysis remains in the cytosol and is broken down into either lactic acid or ethyl alcohol during fermentation. This process allows glycolysis to continue and produce more ATP.

  1. Why does Lactic Acid Fermentation occur in your muscle cells? What type of fermentation occurs when making bread? Why?

Lactic acid fermentation occurs in your muscle cells when there is not enough oxygen to carry out aerobic respiration.

Alcohol fermentation occurs when making bread. Yeast break down glucose to produce ethanol (which evaporates) and CO2 gas (which makes the bread “fluffy”).

  1. Why are anaerobic organisms usually always small and single-celled? Explain.

Small single-celled organisms are small and do not need as much energy to sustain life.

  1. Do plants perform cellular respiration? Why or why not?

Plants do perform cellular respiration using the glucose and oxygen that they produce during photosynthesis.

  1. Using your knowledge of cellular respiration, why does your heart rate and breathing rate increase during physical activity? Why do your muscles sometime burn when working out?

Cellular respiration requires oxygen to power the production of ATP during electron transport. During physical activity, your muscle cells use oxygen at a faster rate. Your breathing rate increases to bring in more oxygen and your heart rate increases to circulate oxygenated blood faster.

  1. Label the diagram on the right with the following terms:
  2. Glucose
  3. Oxygen
  4. ATP
  5. Carbon dioxide
  6. Water
  7. Electrons & Hydrogen
  8. Glycolysis
  9. Krebs Cycle/Citric acid cycle
  10. Electron transport
  11. Mitochondria
  1. Complete the following chart that summarizes the 3 steps of aerobic respiration:

Name of Stage / Location in cell / Oxygen Required? / Reactants / Products / # of ATP Produced
Glycolysis / Cytosol / No / Glucose / ATP
(pyruvic acid & NADH) / 2
Krebs Cycle (Citric Acid Cycle) / Matrix of mitochondria / Yes / (pyruvic acid) / Carbon dioxide, ATP
(NADH & FADH2) / 2
Electron Transport / Cristae of mitochondria / Yes / Oxygen
(NADH & FADH2) / Water & ATP / 34
  1. In Respiration, what is O2 used for? How is water produced? Why is CO2 released?

Oxygen is used to pull electrons through the electron transport chain. The oxygen then combines with hydrogen to form water. Carbon dioxide is released as glucose molecules are broken down.

  1. Why are plants considered “Producers or Autotrophs” and animals are “Consumers or Heterotrophs”?

Autotrophs are organisms that can produce their own food. Heterotrophs are organisms that must eat or consume food for energy because they cannot produce their own.

Photosynthesis

  1. Write the overall chemical equation for photosynthesis (label the reactants & the products).

CO2 + H2O + Sunlight à C6H12O6 + O2

carbon dioxide + water + energy à Glucose + oxygen

(Reactants) (Products)

  1. What is the role of the following items in photosynthesis:
  2. Chloroplast: site of photosynthesis reactions
  3. thylakoid membrane: site of the light reactions
  4. Pigments (chlorophyll a, chlorophyll b, cartenoids): capture energy from the sun & provide electrons for electron transport (light reaction)
  1. Label the diagram on the right with the following terms:
  2. Calvin Cycle
  3. ATP
  4. NADPH
  5. Light
  6. Light Reaction
  7. 02
  8. H20
  9. CO2
  10. PGAL (Sugar)
  1. Complete the following chart that summarizes the 2 steps of photosynthesis:

Reaction / Location / Reactants / Products
Light Reaction / Thylakoid membrane in chloroplasts / Sunlight & water / Oxygen
(NADPH & ATP)
Calvin Cycle (Dark Rxn) / Strom in chloroplasts / Carbon dioxide
(NADPH & ATP) / PGAL à Glucose
  1. In Photosynthesis, what is water used for? What is CO2 used for?

In photosynthesis, water molecules are split and the electrons are used to replace the electrons in chlorophyll that were used in electron transport. Carbon dioxide is used as the carbon source to build molecules of sugar.

  1. What is PGAL? How does this relate to Glucose?

PGAL is half of a glucose molecules. Two molecules of PGAL are needed to make one molecule of glucose.

  1. Why is the dark reaction described as a “Cycle”? How many CO2’s are required to make 1 PGAL?

The “dark reaction” is described as a cycle because the molecule that begins the process (RuBP) is reformed after sugar is formed. This molecule is then reused to make more sugar molecules. Three carbon dioxide molecules are needed to make one PGAL molecule.